A barcode is an optical machine-readable representation of data relating to the object to which it is attached. It can be represented data by varying the widths and spacings of parallel lines as linear or one-dimensional (1D), or by rectangles, dots, hexagons and other geometric in two dimensional patterns (2D). The main functions of bar coding are accuracy and speed. Scanning is much faster than manually entering the series of numbers into a computer with a keyboard or number pad. Barcode system is well-development technology and lower in cost of readers and barcode tags. It is common and relatively standard tools in modern life, specifically, inventory, point-of-sale, stock-take and etc.
RFID systems are being utilized in a great quantity in a multitude of applications. One of the common areas for RFID implementation is product identification, for inventory or for sales. The bar code scanner technology is slowly being replaced by RFID technology. In the simplest of applications, a passive RFID transponder, commonly called a tag or a card, is placed on an object that is to be identified. A RFID reader is then used to obtain information from the tag. The reader, being powered by a power source, typically has a transceiver to transmit and receive signals. The tag also has a transceiver to receive the signal from the reader and to transmit a response back to the reader. The tag is generally passive and powered by the induced electromagnetic field.
The reader is powered and generates a magnetic field from its antenna. When the reader and the tag are within close proximity of each other, the generated magnetic field from the reader is induced into the tag. The tag uses this coupled energy to power its circuitry. The reader transmits an interrogating signal to the tag, and the tag transmits a signal back to the reader in response to the interrogation. The tag may be placed on an item and the response from the tag may be used to simply identify the item.
RFID systems may use active tags which carry their own source of power such as a battery, or passive tags which contain no source of power and instead rely entirely on energy radiated by the reader. Passive tag readers continually or periodically search for the presence of passive tags in the vicinity of the reader by transmitting energy which will activate any tag present. A passive tag does not announce its presence unless activated by the reader.